Observation of the 11N ground state

The ground state of the proton-rich, unbound nucleus 11N was observed, together with six excited states using the multinucleon transfer reaction 10B(14N,13B)11N at 30A MeV incident energy at Grand Accelerateur National d'Ions Lourds. Levels of 11N are observed as well defined resonances in the spectrum of the 13B ejectiles. They are localized at 1.63(5), 2.16(5), 3.06(8), 3.61(5), 4.33(5), 5.98(10), and 6.54(10) MeV above the 10C+p threshold. The ground-state resonance has a mass excess of 24.618(50) MeV; the experimental width is smaller than theoretical predictions.